Search

Scattering scanning near-field optical microscopes (s-SNOMs) based on pseudoheterodyne detection and operating at ambient conditions typically suffer from instabilities related to the variable optical path length of the interferometer arms. These cause strong oscillations in the measured optical amplitude and phase comparable with those of the signal and, thus, resulting in dramatic artifacts. Besides hampering the comparison between the topography and the optical measurements, such oscillations may lead to misinterpretations of the physical phenomena occurring at the sample surface, especially for nanostructured materials. Here, we propose a stabilizing method based on interferometer phase control, which improves substantially the image quality and allows the correct extraction of optical phase and amplitude for both micro- and nanostructures. This stabilization method expands the measurement capabilities of s-SNOM to any slowly time-dependent phenomena that require long-term stability of the system. We envisage that active stabilization will increase the technological significance of s-SNOMs and will have far-reaching applications in the field of heat transfer and nanoelectronics. [ABSTRACT FROM AUTHOR]

The role of the optics of surface and interfaces in the near‐field radiative heat transfer for finite‐layered media and superlattices is reviewed. The definition of surface impedance is compared with effective medium approximations for the dielectric functions. It is shown that the presence of polar materials makes the use of effective medium models ineffective, in particular, when the topmost layer supports surface modes. Furthermore, the effect on the near‐field heat transfer is quantified when approximate methods are used. [ABSTRACT FROM AUTHOR]